Avoid implicit integer cast in Normal::pickBiome()

this throws deprecation warnings on PHP 8.1.

src/world/generator/normal/Normal.php

@@ -123,6 +123,7 @@ class Normal extends Generator{
 	private function pickBiome(int $x, int $z) : Biome{
 		$hash = $x * 2345803 ^ $z * 9236449 ^ $this->seed;
 		$hash *= $hash + 223;
+		$hash = (int) $hash;
 		$xNoise = $hash >> 20 & 3;
 		$zNoise = $hash >> 22 & 3;
 		if($xNoise == 3){

tests/phpstan/configs/phpstan-bugs.neon

@@ -80,3 +80,8 @@ parameters:
 			count: 2
 			path: ../../../src/world/format/io/region/RegionLoader.php
 
+		-
+			message: "#^Casting to int something that's already int\\.$#"
+			count: 1
+			path: ../../../src/world/generator/normal/Normal.php
+